Angiography is the x-ray study of blood vessels. An angiogram uses a dye to make the blood vessels visible under x ray. Angiography is used to detect abnormalities or blockages in the blood vessels (occlusions) throughout the circulatory system and in some organs.

The procedure is commonly used to identify atherosclerosis; to diagnose heart disease; to evaluate kidney function and detect kidney cysts or tumors; to detect an aneurysm (an abnormal bulge of an artery that can rupture), tumor, blood clot, or arteriovenous malformations (abnormals tangles of arteries and veins) in the brain; and to diagnose problems with the retina. It is also used to map the heart or the brain prior to surgery.

Angiography is performed at a hospital. It requires injecting a contrast dye into the blood vessels, making them visible to x ray. The dye is injected by arterial puncture. The puncture is usually made...